Invalid carriage

ABSTRACT

Invalid carriages, e.g., wheelchairs capable of ascending and descending inclines under the muscular control and motive power of a disabled occupant, are provided by the introduction of clutches, gear reduction means and torque enhancement means between the hand rim and driven wheels of an otherwise conventional invalid carriage.

United States Patent 1191 Wada [ Nov. 4, 1975 22 Filed: 21 Appl. No.: 439,962

[ INVALID CARRIAGE '[76] Inventor: Sadae Wada, 3-1, Azateppoba,

Odate, Akita, Japan Feb. 5, 1974 30 Foreign Application Priority om Feb. 5, 1973 Japan 48-15065 52 us. or 280/238; 280/242; 280/250;

1 I 74/322; 74/339; 192/67 P 51 1111. cm ..B62M 25/04; B62M 01/14;

F16H 03/38; F16D 11/04 [58] Field of Search 297/D1G. 4; 280/211, 236, 280/237, 238, 242 WC, 249,250; 74/322,

[56] References Cited UNITED STATES PATENTS 341,237 5/1886 Healey 280/238 578,329

3/1897 Gruber 280/249 1,008,150 11/1911 Holden 74/322 3,195,910 7/1965 Steiner 3,563,568 2/1971 Sasse 3,643,642 2/1972 .lunes 192/67 P X FOREIGN PATENTS OR APPLICATIONS 589,004 6/1947 United Kingdom 280/21] 557,742 8/1923 France 280/238 Primary Examiner-Samuel Scott Assistant ExaminerP. S. Lall Attorney, Agent, or Firm-James C. Haight 5 7] ABSTRACT Invalid carriages, e.g., wheelchairs capable of ascending and descending inclines under the muscular control and motive power of a disabled occupant, are provided by the introduction of clutches, gear reduction means and torque enhancement means between the hand rim and driven wheels of an otherwise conventional invalid carriage.

8 Claims, 4 Drawing Figures M/WMWWWA US. Patent Nov. 4, 1975 Sheet 1 of2 3,917,311

FIG.-2

U.S. Patent Nov. 4, 1975 Sheet 2 of 2 3,917,311

FIG.3

FIGA

INVALID CARRIAGE BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to invalid chairs and more particularly to wheeled invalid chairs capable of going up and down a slope safely and easily without the use of auxiliary motive power.

2. Description of the Prior Art Invalid carriages are now available which are improved in various respects, and several types of invalid carriages which are simple in construction, light in weight and easy to manipulate, such as, for example, being capable of getting in and out of the carriages from its lateral side, preventing feet of the user from slipping out of its step plate, folding it in a compact size, using it as a bed,- are already manufactured and practically used in the art. Also, invalid carriages with inflated tires, invalid carriages having knobs around periphery of the hand rims, invalid carriages with tables, electrically driven invalid carriages, andso on, are already known. However, a number of desirable improvements are still to be added to these invalid carriages. A typical example of these improvements is to enable them to go up and down aslope and steps with users physical strength. In the conventional invalid carriage, it is hard to climb a slope, because greater physical strength is required to rotate the hand rims of the invalid carriage in order to advance it on the slope than is required to propel it on a flat surface, and also because the-invalid carriage is always subjected to grav itational forces to cause it to go downhill while climbing the slope. Further, the conventional invalid carriage is not satisfactorily safe when it descends a slope, because it is liable to-slip on the slope during the operation of a brake and it is somewhat difficult to descend the slope as the brake is operating.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an improved wheeled invalid chair or invalid carriage which is able to easily go up and down a slope merely by rotating hand rims of the invalid carriage with an users physical strength.

'Another object of the present invention is to provide a wheeled invalid chair or an invalid carriage which is able to easily ascend a slope by rotating hand rims of the invalid carriage with an users physical strength and in which reverse rotation of the wheels of the invalid carriage is prevented during the climb of the slope so that safety may be assured.

Still another object of the present invention is to provide a wheeled invalid chair or an invalid carriage which is able to descend a slope slowly so that risks due to acceleration of the invalid carriage during the descent of the slope may be prevented.

Briefly, the foregoing and other objects are attained in accordance with the present invention by the provision of an invalid carriage having a pair of driven wheels and hand rims which are directly connectable to the driven wheels and rotated therewith at the same rate of rotation, and which are also separable so as to be able to rotate the driven wheels at a reduced rotating ratio when the hand rims are rotated. To prevent backward rotation of the driven wheels during the climb of the slope and acceleration of the driven .wheels during the descent of the slope, reduction gears are 2 provided including a worm and worm wheel between the driven wheels and the hand rims.

In the field of mechanical engineering, a number of reduction mechanisms have been proposed, but the reduction mechanism usually functions as an accelerating mechanism if it is reversely rotated. However, in reduction gearing using a worm and a worm wheel, the worm wheel is rotated at a reduced rotational speed if it is rotated from the worm side, however, the worm itself is not caused to be rotated if it is rotated from the worm wheel side. Because of this feature, in accordance with the present invention, a reduction gear comprisinga worm and a worm wheel is connected to the driven wheels so that the invalid carriage can safely ascent and descend slopes.

Supposing that diameters of the driven wheels and the hand rims are in the ratio of 4/5, a physical strength of 5kg applied to the hand rims is converted to 4kg at a point where the driven wheels contact a surface of the slope.

If the reduction ratio of the driven wheels to the hand rim is 1/3, a physical strength of 5kg is applied to the hand rims and the mechanical efficiency is 0.8, then the force acting upon the driven wheels at the point where they contact the surface of the slope may be represented by the following expression:

4kg X 3 X 0.8 9.6kg

As is apparent from the above expression, the force at the contacting point is increased to 2.4 times the initial force applied to the hand rims by reducing the rotating speed of the driven wheels by 1/3. Thus, the force of 4kg becomes 9.6kg and the torque is increased. Therefore, the invalid carriage in accordance with the present invention can ascend a slope as long as the friction at the contacting surface of the driven wheels is smaller, than the torque of the driven wheels. It is further obvious that the invalid carriage can ascend the slope much easier with a force of 9.6kg than with a force of 4kg.

In reduction gearing using the worm and the W0 wheels, the reduction ratio is normally l/lO to l/lOO. Thus, in order to make the reduction ratio of the driven wheels to the hand rims 1/3, the driven wheels must be accelerated to rotate at the ratio of 10/3 by means of chain wheels and bevel gears if the reduction ratio of the reduction gears is l/lO. Then, the reduction ratio represented by the following expression is obtained:

l/lO X 10/3 =1/3 Obviously, this reduction ratio is only one the example, and it is possible to design invalid carriages having various reduction ratios of the driven wheels to the hand rim in compliance with requests by the application of the principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS Various other objects, features and attendant advantages'of the present invention will be more fully appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein like reference numerals refer to corresponding parts in the several Figures, and in which:

FIG. 1 is a side view of an invalid carriage in accordance with the present invention;

FIG. 2 is a rear side view of an invalid carriage in accordance with the present invention;

3 FIG. 3 is an enlarged partial sectional view of a reduction mechanism associated with a driven wheel and a hand rim taken along the line 3 3 of FIG. 1, showing the condition of reducing rotating speed of the driven wheels; and

FIG. 4 is an enlarged partial sectional view similar to FIG. 3 in which the reduction mechanism is disengaged from the driving wheel and the hand rim is directly connected to the driving wheel.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to the drawings, and more particularly to FIGS. 1 and 2 thereof, the invalid carriage generally indicated by the reference numeral of the present invention is shown as including a seat-carrying upright framework 11 which is commensurate in its Width and length, a pair of spaced smaller diameter front wheels 12 supported or joumalled in front of the framework 11, a pair of spaced larger diameter driven wheels 13 and 14 having hand rims 15 and 16 respectively for manually driving the driven wheels 13 and 14 which are rotatably mounted on an axle 17 extending laterally to the framework 11 at the rearward region thereof, and a pair of reduction gear assemblies 18 and 19 which can be coupled to each of the driven wheels 13 and 14 so as to reduce the rotating ratio of the driven wheels 13 and 14 to the hand rims 15 and 16 when the invalid chair l0 ascends a slope by manually rotating the hand rims 15 and 16. As shown in FIG. 2, the driven wheels 13 and 14, and the hand rims 15 and 16 are disposed at both sides of the invalid chair 10 so that they may be easily gripped and rotated by users hands. The reduction gear boxes 18 and 19 are supported on a rectangular base frame 20 of the framework 11 at the rear portion thereof and associated with power transmitting mechanisms hereinafter described which are preferably disposed at an open space below a seat portion of the framework 11. The invalid carriage 10 in accordance with the present invention is preferably constructed to make its center of gravity lower than that of invalid carriages designed solely for propelling along a flat surface so that the stability thereof may be assured, since the stability of an invalid carriage is reduced when it goes up a slope.

Referring now to the power transmitting mechanisms and the reduction gear assemblies 18 and 19 associated with the driven wheels 13 and 14 and the hand rims 15 and 16 shown in FIGS. 3 and 4, the hand rim l5 and the driven wheel 13 are provided with holes 21 and 22 at bosses 23 and 24 thereof, and are mounted on the axle 17 by means of a bushing 25 and a sleeve 26 having a flange 27 at an end thereof. The flange 27 includes a pin 28 projected from the rear surface thereof which is inserted into the hole 21 of the hand rim 15. The pin 28 may be penetrated into the hole 22 of the driven wheel 13 by an operation of clutch lever 29. The sleeve 26 is rotatable around the axle 17 with the hand rim 15 when it is rotated by users hands. Around the sleeve 26, a clutch member, generally indicated by the reference numeral 30, is secured by a key 50, which includes a front portion 31 rotatable around the bushing 25 being independent of the rotating motion of a rear portion 32 of the clutch member 30. The front portion 31 of the clutch member includes pins 33 and 34 which may be respectively penetrated into the hole 22 of the driven wheel 13 and a hole 56 of a chain wheel 57 rotatably mounted around the front portion 31 of the clutch member 30. The rear portion 32 of the clutch member 30 includes a pin 35 which may be penetrated into a hole 36 of chain wheel 37 rotatably mounted around the rear, portion 32 of the clutch member 30. The clutch member 30 is moveable horizontally along the axle 17 by the operation of lever 29 so that it may be engaged or disengaged with the driven wheel 13 by the penetration of pins 33, 34 and 35 into the holes 22, 56 and 36 or extraction therefrom as shown in FIGS. 3 and 4.

The reduction gear box 18 includes a worm and worm gearing (not shown) which is of conventional type, and has an input shaft 41 provided with a chain sprocket 42 and an output shaft 43 provided with a bevel gear 44 engaging with a bevel gear 45 coaxially mounted on a shaft 46 having a chain sprocket 47. The chain sprocket 42 and the chain wheel 37 are con-. nected by chain 48, while chain sprocket 47 and the chain wheel 57 are connected by chain 49.

Referring now to the operation of the invalid carriage in accordance with the present invention, when the clutch lever 29 is operated to make the clutch member 30 engage with the driven wheel 13 as shown in FIG. 3, the pins 34 and 35 of the clutch member 30 are respectively engaged with the chain wheels 57 and 37. When the hand rim is manually rotated, the rear portion 32 of v the clutch member 30 secured to the sleeve 26, is rotated to cause the chain wheel 37 to be rotated by the pin 35, and the rotation of the chain wheel 37 is transmitted to the chain sprocket 42 of the reduction gears by means of the chain 48. Then, the worm and the worm wheel in the reduction gear box 18 are rotated to cause output shaft 43 having the bevel gear 44 at the terminating end thereof to rotate at the reduced speed, and the chain sprocket 47 connected to the output shaft 43 of: the reduction gear by means of the bevel gear 45 is rotated, and in turn the front portion 31 of the clutch member 30 engaging with the chain wheel 57 and the driven wheel 13 is rotated by the chain 49, thereby the driven wheel 13 is rotated at reduced speed by the hand rim 15 through the power transmitting mechanisms and reduction gear assemblies described the above.

When the invalid carriage in accordance with the present invention is adapted for propulsion along a flat surface, the clutch member 30 is disengaged from the driven wheel 13 by operation of the clutch lever 29, and the chain wheels 57 and 37 are freed from engagement with the pins 34 and 35 of the clutch member 30 as shown in FIG. 4. Then, the hand rim l5 and the driven wheel 13 are united by the penetration of the pin 28 into the hole 22 of the driven wheel 13 and it can be rotated with the hand rim 15.

The weight of the invalid carriage in accordance with the present invention may be somewhat increased,

since the reduction gears and the driving mechanisms associated therewith are mounted on the carriage. However, it is possible to improve this defect by selecting the materials adapted to use for the construction of the invalid carriage.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. In an invalid carriage having a seat-carrying upright framework with an axle extending laterally across said framework, a pair of spaced driven wheels rotatably supported on said axle at both sides of said framework and a pair of spaced hand rims rotatably supported on said axle adjacent to said driven wheels for manually rotating said driven wheels, the improvement which comprises:

means for making a direct connection between said driven wheels and hand rims for simultaneous rotation therebetween;

reduction gear means having input shafts having means for coupling to said hand rims and output shafts having means for coupling to said drive wheels for positively reducing the rotation of said driven wheels with respect to said hand rims when said hand rims are connected to said driven wheels through said reduction gear means, said reduction gear means being independent of said direct connection means; and

clutch means for simultaneously actuating said direct connection means and disconnecting said reduction gear means or deactuating said direct connection means and connecting said reduction gear means,

whereby the use of the reduction gear means increases the force applied to the hand rims in ascending a slope and restrains acceleration of the carriage in descending a slope.

2. An invalid carriage according to claim 1, wherein said reduction gear means comprises worms and worm wheels, and said input shafts are connected to said worms and said output shafts are connected to said wonn wheels.

3. An invalid carriage according to claim 2, further comprising means for increasing the rotational force taken off the output shaft of said reduction gear means and transmitting the increased rotational force to said driven wheels.

4. An invalid carriage according to claim 3, wherein said input shafts of said reduction gears include chain sprockets driven by chains engaging chain wheels which are driven by said hand rims.

5. An invalid carriage according to claim 4, wherein said means for increasing the rotational force is a gear assembly comprising bevel gears, chain sprockets, chains and chain wheels.

6. An invalid carriage according to claim 1, further comprising means for increasing the rotational force taken off the output shaft of said reduction gear means and transmitting the increased rotational force to said driven wheels.

7. An invalid carriage according to claim 6, wherein said input shafts of said reduction gears include chain sprockets driven by chains engaging chain wheels which are driven by said hand rims.

8. An invalid carriage according to claim 6, wherein said means for increasing the rotational force is a gear assembly comprising bevel gears, chain sprockets,

chains and chain wheels. 

1. In an invalid carriage having a seat-carrying upright framework with an axle extending laterally across said framework, a pair of spaced driven wheels rotatably supported on said axle at both sides of said framework and a pair of spaced hand rims rotatably supported on said axle adjacent to said driven wheels for manually rotating said driven wheels, the improvement which comprises: means for making a direct connection between said driven wheels and hand rims for simultaneous rotation therebetween; reduction gear means having input shafts having means for coupling to said hand rims and output shafts having means for coupling to said drive wheels for positively reducing the rotation of said driven wheels with respect to said hand rims when said hand rims are connected to said driven wheels through said reduction gear means, said reduction gear means being independent of said direct connection means; and clutch means for simultaneously actuating said direct connection means and disconnecting said reduction gear means or deactuating said direct connection means and connecting said reduction gear means, whereby the use of the reduction gear means increases the force applied to the hand rims in ascending a slope and restrains acceleration of the carriage in descending a slope.
 2. An invalid carriagE according to claim 1, wherein said reduction gear means comprises worms and worm wheels, and said input shafts are connected to said worms and said output shafts are connected to said worm wheels.
 3. An invalid carriage according to claim 2, further comprising means for increasing the rotational force taken off the output shaft of said reduction gear means and transmitting the increased rotational force to said driven wheels.
 4. An invalid carriage according to claim 3, wherein said input shafts of said reduction gears include chain sprockets driven by chains engaging chain wheels which are driven by said hand rims.
 5. An invalid carriage according to claim 4, wherein said means for increasing the rotational force is a gear assembly comprising bevel gears, chain sprockets, chains and chain wheels.
 6. An invalid carriage according to claim 1, further comprising means for increasing the rotational force taken off the output shaft of said reduction gear means and transmitting the increased rotational force to said driven wheels.
 7. An invalid carriage according to claim 6, wherein said input shafts of said reduction gears include chain sprockets driven by chains engaging chain wheels which are driven by said hand rims.
 8. An invalid carriage according to claim 6, wherein said means for increasing the rotational force is a gear assembly comprising bevel gears, chain sprockets, chains and chain wheels. 